Correct Option: C

Trypsin is an enzyme. The pancreas adds a collection of protein-cutting enzymes, with trypsin playing the central role, that chop the protein chains into pieces just a few amino acids long. Then, enzymes on the surfaces of intestinal cells and inside the cells chop them into amino acids, ready for use throughout the body. Trypsin uses a special serine amino acid in its protein-cutting reaction, and is consequently known as a serine protease.